This invention relates to power sources in general and more particularly to an electric dc source using fuel cells or fuel batteries connected in series or in series and parallel.
For dc drives it is common practice to connect batteries electrically in series and/or in parallel in order to vary the voltage. The same also applies to fuel cells or fuel batteries, i.e. batteries consisting of several individual fuel cells or groups of fuel cells. Fuel cells are electrochemical arrangements in which the free enthalpy of the oxidation of a fuel is converted directly into electrical energy and the reactants, i.e. fuel and oxidizing agent, are fed to the cell continuously. Gaseous reactants such as hydrogen and oxygen, or air, generally are used for this purpose.
Connecting the batteries of this type in series or in parallel is done in most cases by mechanical switchgear which, however, is quite noisy, thus representing a certain pollution of the environment. While power electronics like thyristor switches and/or dc regulators may also be used for switching, they are relatively bulky, and in addition, not entirely noiseless either.
It is thus an object of the present invention to provide an electric dc source utilizing fuel cells or fuel batteries connected in series or in series and parallel in which, not only is quiet operation made possible, but large power electronics may also be dispensed with.